Compound semiconductors are semiconductor compounds composed of elements from two or more different groups of the Periodic Table of Elements. For example, III-V (or 13-15) compound semiconductors are composed of elements from Group 13 (B, Al, Ga, In) and from Group 15 (N, P, As, Si, Bi) of the Periodic Table of Elements. The range of possible formulae is quite broad because these elements can form binary (two elements, e.g., GaAs), ternary (three elements, e.g., InGaAs) and quaternary (four elements, e.g., AlInGaP).
III-V compound semiconductors, as well as other classes of compound semiconductors, are receiving renewed attention for use as channel materials for advanced ultra large scale integration (ULSI) digital logic applications due to their high electron hole mobility relative to channel materials composed of silicon. Despite having higher channel mobility than conventional silicon based devices, it is known that Group V elements such as As evaporate from the surface of a III-V compound semiconductor upon high temperature annealing (greater than 800° C.), leaving surface defects including surface pitting in the III-V compound semiconductor.
There are no known inexpensive and robust manufacturing working solutions to prevent surface decomposition of III-V compound semiconductors during high temperature processing. Such processing is required to electrically activate ion implanted dopants within the III-V compound semiconductor and to improve dielectric properties of a gate dielectric layer that typically overlays the III-V compound semiconductor.
Additionally, preventing surface decomposition of III-V compound semiconductors is a pre-requisite to fabricate high performance semiconductor devices, such as, for example, metal oxide semiconductor field effect transistors (MOSFETs), in III-V compound semiconductors. Severe surface decomposition of III-V compound semiconductors during high temperature processing can cause surface pitting, and/or surface erosion of the gate dielectric that is located above the compound semiconductor. The decomposition of the III-V compound semiconductor leads to the degradation of the electrical characteristics of the compound semiconductor as well as the devices that are fabricated thereon.